US2025051892A1PendingUtilityA1
Hot-rolled steel for hyper tube and manufacturing method therefor
Est. expiryDec 20, 2041(~15.4 yrs left)· nominal 20-yr term from priority
C21D 8/02C22C 38/04C22C 38/02C21D 2211/009C21D 2211/005C21D 9/46C21D 8/0226C21D 6/008C21D 6/005C22C 38/34C22C 38/38C22C 38/12C22C 38/14C22C 38/16C22C 38/08C21D 8/0263C21D 8/0205
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Claims
Abstract
An aspect of the present invention may provide a hot-rolled steel sheet that is excellent in terms of yield strength, vibration damping ratio, weldability, and weld site-low temperature toughness and thus has physical properties suitable for use in a vacuum train tube maximizing energy efficiency of a vacuum train; and a manufacturing method therefor.
Claims
exact text as granted — not AI-modified1 . A hot-rolled steel sheet for a vacuum train tube comprising, by weight, carbon (C): 0.03 to 0.11%, silicon (Si): 1.0 to 2.0%, manganese (Mn): 1.2 to 2.2%, a balance of Fe, and inevitable impurities,
wherein a microstructure comprises a composite structure in which pearlite is dispersed in a matrix structure of ferrite.
2 . The hot-rolled steel sheet of claim 1 , wherein an average particle size (D F , μm) of the ferrite and an average aspect ratio (A F ) of the ferrite satisfy the following Relational expression 1:
7
≤
D
F
/
A
F
≤
20
[
Relational
expression
1
]
3 . The hot-rolled steel sheet of claim 2 , wherein the average particle size (D F ) of the ferrite satisfies a range of 8 to 20 μm.
4 . The hot-rolled steel sheet of claim 2 , wherein the average aspect ratio (A F ) of the ferrite is 2 or less.
5 - 7 . (canceled)
8 . The hot-rolled steel sheet of claim 1 , wherein a total amount of titanium (Ti), niobium (Nb), and vanadium (V), inevitably included in the hot-rolled steel sheet, is less than 0.01% (including 0%).
9 . The hot-rolled steel sheet of claim 1 , wherein the hot-rolled steel sheet comprises one or more selected from chromium (Cr), nickel (Ni), copper (Cu), molybdenum (Mo), and tungsten (W), in a total amount of 1.0% or less (including 0%).
10 . The hot-rolled steel sheet of claim 1 , wherein the hot-rolled steel sheet satisfies any one or more of the following relational expressions 2 to 5 for the hot-rolled steel sheet:
355
≤
11
+
394
*
D
F
(
-
0.5
)
+
448
*
[
C
]
+
94
*
[
Si
]
+
69
*
[
Mn
]
[
Relational
expression
2
]
100
≤
186
-
240
*
D
F
(
-
0.5
)
-
121
*
[
C
]
-
13.2
*
[
Si
]
+
13.7
*
[
Mn
]
[
Relational
expression
3
]
27
≤
476
-
95.22
*
ln
(
D
F
)
-
220
*
[
C
]
-
88
*
[
Si
]
[
Relational
expression
4
]
35
≤
9.5
+
5.2
*
[
C
]
+
5.8
*
[
Mn
]
+
13.1
*
[
Si
]
[
Relational
expression
5
]
where D F is an average particle size (μm) of ferrite included in the hot-rolled steel sheet, [C], [Si], and [Mn] are an amount of carbon (C), an amount of silicon (Si), and an amount of manganese (Mn), included in the hot-rolled steel sheet (wt %), and, when a component thereamong is not included, brackets including the component are substituted with zero (0).
11 . The hot-rolled steel sheet of claim 1 , wherein the microstructure of the hot-rolled steel sheet comprises 60 to 90 area % of ferrite, 10 to 40 area % of pearlite, and an inevitable structure.
12 . The hot-rolled steel sheet of claim 1 , wherein yield strength of the hot-rolled steel sheet is 350 MPa or more, and
a Charpy impact energy of the hot-rolled steel sheet at −20° C. is 27 J or more.
13 . The hot-rolled steel sheet of claim 1 , wherein a vibration damping ratio measured at a frequency of 1650 Hz in a flexural vibration mode, after processing the hot-rolled steel sheet into a specimen with a length*width*thickness of 80 mm*20 mm*2 mm, is 100*10-6 or more.
14 . The hot-rolled steel sheet of claim 1 , wherein an electrical resistivity of the hot-rolled steel sheet is 35*10 −8 Ωm or more.
15 . The hot-rolled steel sheet of claim 1 , wherein a yield ratio in a direction, parallel to a rolling direction of the hot-rolled steel sheet, is 0.8 or less, and
a yield ratio difference (ΔYR) in each direction, defined by the following relational expression 6, is 10% or less:
Δ
YR
=
(
❘
"\[LeftBracketingBar]"
YR
RD
-
YR
TD
❘
"\[RightBracketingBar]"
*
100
)
/
YR
RD
[
Relational
expression
6
]
where YR RD is a yield ratio in a direction, parallel to a rolling direction of the hot-rolled steel sheet, YR TD is a yield ratio in a direction, perpendicular to the rolling direction of the hot-rolled steel sheet, and |YR RD −YR TD | is an absolute value of a difference between the yield ratio (YR RD ) in a direction, parallel to the rolling direction and the yield ratio (YR TD ) in a direction, perpendicular to the rolling direction.
16 . The hot-rolled steel sheet of claim 1 , wherein, in a welded portion formed by welding the hot-rolled steel sheet using submerged arc welding,
a Charpy impact energy of the welded portion at −20° C. is 27 J or more, and a fraction of an M-A phase included in the welded portion is 5 area % or less (including 0%).
17 . The hot-rolled steel sheet of claim 1 , wherein a thickness of the hot-rolled steel sheet is 10 mm or more.
18 . A method for manufacturing a hot-rolled steel sheet for a vacuum train tube, comprising:
heating a slab to a heating temperature (T 1 ) of 1100° C. to 1300° C., wherein the slab includes, by weight, carbon (C): 0.03 to 0.11%, silicon (Si): 1.0 to 2.0%, manganese (Mn): 1.2 to 2.2%, a balance of Fe, and inevitable impurities; hot-rolling the heated slab at a finish rolling temperature (T 2 ) of 900° C. to 1000° C. to provide a hot-rolled steel sheet; and coiling the hot-rolled steel sheet at a coiling temperature (T 3 ) of 600° C. to 700° C., wherein the finish rolling temperature (T 2 ) and the coiling temperature (T 3 ) satisfy the following Relational expression 7:
10
≤
-
101.9
+
0.103
*
[
T
2
]
+
0.0339
*
[
T
3
]
-
61.9
*
[
C
]
-
190.2
*
[
Nb
]
≤
20
[
Relational
expression
7
]
where [T 2 ] and [T 3 ] are the finish rolling temperature (T 2 , ° C.) and the coiling temperature (T 3 , ° C.), [C] and [Nb] are an amount of carbon (C) and an amount of niobium (Nb), included in the hot-rolled steel sheet (wt %), and, when a component thereamong is not included, brackets including the component are substituted with zero (0).
19 - 21 . (canceled)
22 . The method of claim 18 , wherein a total amount of titanium (Ti), niobium (Nb), and vanadium (V), inevitably included in the slab, is less than 0.01% (including 0%).
23 . The method of claim 18 , wherein the slab comprises one or more selected from chromium (Cr), nickel (Ni), copper (Cu), molybdenum (Mo), and tungsten (W), in a total amount of 1.0% or less (including 0%).
24 . The method of claim 18 , wherein a thickness of the hot-rolled steel sheet is 10 mm or more.Join the waitlist — get patent alerts
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